Sleep... To Rest, And Shrink Your Brain?

Article - Science

Sleep... To Rest, And Shrink Your Brain?

We all know a good night's sleep leaves us fresh and rested for the new day ahead. But what if one way to rejuvenate ourselves - is by shrinking the brain! Sounds odd?

Research by scientists at the Wisconsin Centre for Sleep and Consciousness studied the brains of mice while they were awake and asleep. They correlated with data for human beings and found that the synapses or connections between brain cells, expand and grow during the day when our brain is active.

However, at night as we sleep, these synapses shrink by almost 20%. This helps consolidate our memories and also makes way for more learning and growth.

What Happens When We Sleep?

When our body is at rest, it gets a chance to recover from all the activity and stress we've put it through over the course of the day. But, our brain can never be at complete rest, since it controls several biological functions like breathing. This means a part of the brain is always 'on'.

Sleep also enables our brains to organize the data it has gathered during the day and reset itself for the next day. As we react to the outside world, there is a lot of information traffic in the brain. This flows through pathways in the brain, otherwise known as synapses. The synapses are basically junctions between brain cells, which strengthen as they are used.

But even synapses cannot be overused. In fact, information overload can cause serious burn outs. That's where sleep comes to the rescue. The relatively lesser brain activity allows the synapses to contract and relax. Only the most important memories are retained in large permanent synapses, while the temporary ones shrink or are pruned out. This creates space for new growth and fresh data from the next day.

Measuring Brain Activity

It took the team over 4 years of hard work to reconstruct images of mice brains. They used a high tech electron microscope to scan and study the mice as they were awake and later, as the animals slept. In 4 years, they were able to study near 7000 synapses and measure the changes in their size. They found over 80% of the synapses shrunk as the mice slept and grew when they were awake.

This proved the "synaptic homeostasis hypothesis” or SHY which was first suggested over 10 years ago. Our brain uses the quiet time when we sleep, to normalize the synapses which were activated during the day. This natural process is a smart way to keep our brains alert and ready for new experiences. Conversely, lack of sleep could cause more strain and overload our brain.

So remember, sleep well and stay fresh! Check out this interesting TED-Ed video on sleep.